The Report consists of seven chapters. Chapter 1 describes the scientific facts and impacts of climate change and analyzes its status quo and actions as well as the key role of energy transition in addressing it. Climate service for energy is needed to support the transition to clean energy. This chapter is jointly written by WMO and GEIDCO. Chapter 2 explains the framework and theory of GEI mitigation and puts forward its mechanisms and pathways. Chapter 3 deals with the quantitative analysis of the characteristics and mitigation value of the GEI system by using a comprehensive assessment modelling framework in conjunction with energy system and power system optimization models. Chapter 4 focuses on the GEI mitigation technology portfolio, as well as the development trend and combined use of such technologies as clean replacement, electricity replacement, grid interconnection, energy efficiency enhancement, and carbon removal. Chapter 3 and 4 are jointly written by IIASA and GEIDCO. Chapter 5 studies and proposes key mitigation actions through energy interconnection in different continents based on their respective conditions of climate, resource endowment, and energy and power development. Chapter 6 analyzes the contribution of GEI to economy, society, climate, environment, health and sustainable development. Chapter 7 suggests some innovative mechanisms for addressing climate change, including linking mitigation targets with integrated policy instruments, mobilizing finance resources through the electricity-carbon market, accelerating major projects’ implementation by an innovative mode of “electricity, mining, metallurgy, industry and trade” and adopting new approaches for universal power access to enhance climate resilience.